Any ideas for a cheap cute ren costume?

You could try Salvation Army and get some dresses and old boots or sandals you could fix up to make peasant clothes. I suggest looking online for pictures of different dresses to see what you could make.

I was thinking about being a doctor, I made a silent hill costume for halloween, and was going to maybe make a cheap mask, and put a tail on it to keep away flies

If you go the route of a doctor for a Ren fair, remember... you're going to be swathed from head to toe in black and have your face covered in a white mask that looks somewhere between an owl and a heron.

Although, who am I kidding - plague doctors are awesome. XD Best of luck.

Haha true they wore black, but my costume is uh.. beige i think, with blood splatter, black blood and brown paint (to make it look dirty) I was hoping to go for a doctor that lost a bunch of patients.. I could also maybe go as an elf.. or something, I just dont want to be called a "Squirrel" again because I wear my black fox tail I bought there 4 years ago.

I've never been to one but I want to go so badly. ;__;